Going through the lathe and cleaning while fixing the few issues that I have found, I realized that, while I thought I misplaced them, my lathe did not come to me with headstock clamp pads, #14 in this picture:
I ordered some on eBay, but no matter how I tried to explain to the seller, he could not give me a good measurement of the distance across the machined surfaces. So, what I got were, of course, too wide for my vintage of 9". And I have not found another pair that I think might work.
My lathe had the headstock clamped against the through holes, which I don't think is great as it could lead to a cracked bed. At this point my plan is to use a friends mill
(hi Provincial!) and shorten these two to the correct dimensions. I can't think of any reason not to do it this way, but if someone has a different idea, I would love to hear it.
EDIT: It looks like I can get these cleaned up enough with my little Unimat, so I should be good to go here pretty quick. I think that they aren't the wrong size so much as bunged up enough to hinder things.